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Numerical Investigation of the Evaporation and Mixing of UWS in a Diesel Exhaust Pipe

Authors: Tae Hyun Ahn, Gyo Woo Lee, Man Young Kim

Abstract:

Because of high thermal efficiency and low CO2 emission, diesel engines are being used widely in many industrial fields although it makes many PM and NOx which give both human health and environment a negative effect. NOx regulations for diesel engines, however, are being strengthened and it is impossible to meet the emission standard without NOx reduction devices such as SCR (Selective Catalytic Reduction), LNC (Lean NOx Catalyst), and LNT (Lean NOx Trap). Among the NOx reduction devices, urea-SCR system is known as the most stable and efficient method to solve the problem of NOx emission. But this device has some issues associated with the ammonia slip phenomenon which is occurred by shortage of evaporation and thermolysis time, and that makes it difficult to achieve uniform distribution of the injected urea in front of monolith. Therefore, this study has focused on the mixing enhancement between urea and exhaust gases to enhance the efficiency of the SCR catalyst equipped in catalytic muffler by changing inlet gas temperature and spray conditions to improve the spray uniformity of the urea water solution. Finally, it can be found that various parameters such as inlet gas temperature and injector and injection angles significantly affect the evaporation and mixing of the urea water solution with exhaust gases, and therefore, optimization of these parameters are required.

Keywords: Evaporation, Injection, Selective Catalytic Reduction (SCR), Thermolysis, UWS (Urea-Water-Solution).

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1096217

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References:


[1] M. Y. Kim, Performance Prediction of SCR-DeNOx System for Reduction of Diesel Engine NOx Emission, Transactions of the KSAE, vol. 11, no. 3, pp. 71-76, 2003.
[2] J. H. Kim, M. Y. Kim, and H. G. Kim, NO2-Assisted Soot Regeneration Behavior in a Diesel Particulate Filter with Heavy-Duty Diesel Exhaust Gases, Numerical Heat Transfer, Part A, vol. 58, no. 9, pp. 725-739, 2010.
[3] S. Y. Lee, M. Y. Kim, C. H. Lee, and Y. B. Park, Numerical Investigation of the Urea Melting and Heat Transfer Characteristics with Three Different Types of Coolant Heaters, Transactions of the KSAE, vol. 20, no. 4, pp. 125-132, 2012.
[4] B. K. Yun and M. Y. Kim, Modeling the Selective Catalytic Reduction of NOx by Ammonia over a Vanadia-based Catalyst from Heavy Duty Diesel Exhaust Gases, Applied Thermal Engineering, vol. 50, pp. 152-158, 2013
[5] J. Y. Kim, S. H. Ryu, and J. S. Ha, Numerical Prediction on the Characteristics of Spray-Induced Mixing and Thermal Decomposition of Urea Solution in SCR System, in:Proc. 2004 Fall Technical Conference of the ASME Internal Combustion Engine Division, Long Beach, California USA, 2004.
[6] F. Birkhold, U. Meingast, P. Wassermann, and O. Deutschmann, Modeling and Simulation of the Injection of Urea-Water-Solution for Automotive SCR DeNOx-Systems, Appl. Catal. B: Environ., vol. 70, pp. 119-127, 2007.
[7] S. J. Jeong, S. J. Lee, and W. S. Kim, Numerical Study on the Optimum Injection of Urea-Water Solution for SCR DeNOx System of a Heavy-Duty Diesel Engine to Improve DeNOx Performance and Reduce NH3 Slip, Environmental Engineering Science, vol. 25, no. 7, 2008.
[8] Y. J. Choi, J. M. Woo, D. J. Kim, and J. K. Lee, Effects of the NOx Reduction with Swirl Angle of a Twin-fluid Nozzle using Dual Supplying Air in Urea-SCR System, Proceedings of the KSME Fall Conference, vol. 9, pp. 2205-2210, Pyeongchang, 2009. 11. 4-6.
[9] I. G. Hwang, C. L. Myung, S. S. Park, K. S. Lee, and J. I. Park, Investigation on the Flow and Spray Characteristics of Urea SCR System in Light Duty Diesel Engine to Improve NOx Reduction Efficiency, Proceedings of the KSAE Annual Conference and Exhibition, pp. 675-678, Incheon, 2009. 11. 24-26.
[10] M. Koebel, M. Elsener, and T. Marti, NOx-Reduction in Diesel Exhaust Gas with Urea and Selective Catalytic Reduction, Comb. Sci. and Techn. vol. 121, pp. 85-102, 1996.
[11] D. S. Yim, S. J. Kim, J. H. Baik, I. Nam, Y. S. Mok, J. W. Lee, B. K. Cho, and S. H. Oh, Decomposition of Urea into NH3 for the SCR Process, Ind. Eng. Chem. Res. vol. 43, no. 16, pp. 4856-4863, 2004.
[12] M. Koebel, M. Elsener, and M. Kleemann, Urea-SCR: A Promising Technique to Reduce NOx Emissions from Automotive Diesel Engines, Catalysis Today, vol. 59, pp. 335-345, 2000.
[13] AVL FIRE, CFD-Solver-v2011_Lagrangian-Multiphase, 2011.
[14] H. Strom, A. Lundstrom, and B. Andersson, Choice of Urea-Spray Models in CFD Simulations of Urea-SCR Systems, Chemical Engineering Journal, vol. 150, no. 1, pp. 69-82, 2009.
[15] A. D. Gosman and E. Ioannides, Aspects of Computer Simulation of Liquid-Fueled Combustors, AIAA, pp. 81-323, 1981.
[16] R. J. Kee, F. M. Rupley, E. Meeks, and J. A. Miller, Chemkinā…¢: A Fortran Chemical Kinetics Package for the Analysis of Gas-Phase Chemical and Plasma Kinetics, Sandia National Laboratories, Livermore, CA 94551-0969, 1996.
[17] D. Kuhnke, Spray/Wall-Interaction Modelling by Dimensionless DataAnalysis, Shaker Verlag, 2004. ISBN 3-8322-3539-6.
[18] F. Birkhold, U. Meingast, and P. Wassermann, Analysis of the Injection of Urea-Water-Solution for Automotive SCR DeNOx-Systems: Modeling of Two-Phase Flow and Spray/Wall-Interaction, SAE 2006-01-0643.
[19] M. Koebel and E. O. Strutz, Thermal and Hydrolytic Decomposition of Urea for Automotive Selective Catalytic Reduction Systems: Thermochemical and Practical Aspects, Ind. Eng. Chem. Res., vol. 42, no. 10, pp. 2093-2100, 2003.
[20] H. Weltens, H. Bressler, F. Terres, H. Neumaier, and D. Rammoser, Optimization of Catalytic Converter Gas Flow Distribution by CFD Distribution. Society of Automotive Engineers, SAE 930780, 1993.
[21] S. J. Jeong, S. J. Lee, W. S. Kim, and C. B. Lee, Numerical Study on the Injector Shape and Location of Urea-SCR System of Heavy-duty Diesel Engine for Preventing NH3 Slip, Transactions of the KSAE, vol. 14, no. 1, pp. 68-78, 2006.